PhD Studentship: Climatic consequences of geologically realistic methane emissions from large igneo

Large Igneous Provinces (LIPs) are often associated with global climate change. The best-studied example is the association between the Paleocene-Eocene Thermal Maximum (PETM) and the North Atlantic Igneous Province (NAIP). The PETM is an abrupt global warming and ocean acidification event caused by a major carbon-cycle perturbation. The NAIP supplied carbon-based greenhouse gases to the atmosphere by two main mechanisms. Thermogenic methane formed when shallow igneous sills intruded sedimentary rock with an organic component, and reaches the atmosphere through hydrothermal vents. Carbon dioxide was released from both intruded and erupted magma. Knowing the rates of methane and carbon dioxide emission is of critical importance in judging between this and other mechanisms of carbon release in triggering the PETM.

Existing studies of the LIP methane source provide good estimates of the total mass of carbon released, but the temporal fluctuations in emission rate remain unclear. On the other hand, climate modelling studies have placed bounds on carbon emission rates that would be required to match observed warming and ocean acidification, but they cannot judge whether such rates could feasibly be delivered by the NAIP.

This project will build on work recently completed at the University of Birmingham to determine geologically reasonable methane emission rate scenarios for LIPs. The new framework has three key components. First, we have assembled a large database of sill and host-rock characteristics measured in well-explored parts of LIPs, including the NAIP. Secondly, we have developed a new parameterization of kinetic maturation modelling that permits rapid computation of methane and carbon dioxide generation and expulsion. Thirdly, we have incorporated cutting-edge research into the mantle melt generation processes to constrain rate of sill intrusion across the NAIP. Together, these innovations allow stochastic modelling of carbon-based gas emissions from a sill-and-lava province, in order to determine geologically realistic gas emission rate histories.

The project will use earth system modelling to link the new, realistic methane emission histories to sedimentary records of climate, warming, ocean acidification, and environmental change across the PETM. cGENIE, an Earth system model of intermediate complexity with state-of-the-art representations of biogeochemistry and carbon cycling, will be used to investigate how the estimated range of methane emission scenarios translates in sea surface and deep sea temperature, magnitude and duration of the carbon isotope excursion, difference between marine and terrestrial carbon isotope records, and changes in the patterns of ocean pH and deep sea carbonate burial. Emphasis will be placed on thoroughly exploring how the range of plausible methane emission scenarios maps into model predictions. Observations and modelling predictions will then be compared to assess the role of LIP-derived carbon-based greenhouse gases in forcing various climate change events, beginning with the PETM-NAIP association, then widening in scope to other cases.

Funding Notes

In addition to completing an online application form, you will also need to complete and submit the CENTA studentship application form available from www.centa.org.uk.

CENTA studentships are for 3.5 years and are funded by the Natural Environment Research Council (NERC). In addition to the full payment of their tuition fees, successful candidates will received the following financial support.

Annual stipend, set as £14,553 for 2017/18

Research training support grant (RTSG) of £8,000

CENTA students are required to undertake 45 days training throughout their PhD including a 10 day placement.

References

• T Dunkley Jones, DJ Lunt, DN Schmidt, A Ridgwell, A Sluijs, PJ Valdes, M Maslin. Climate model and proxy data constraints on ocean warming across the Paleocene–Eocene Thermal Maximum. Earth-Science Reviews 125 (2013) 123–145.
• Hülse, D., S. Arndt, J.D. Wilson, G. Munhoven A. Ridgwell. Understanding the causes and consequences of past marine carbon cycling variability through models. Earth-Science Reviews 171 (2017) dx.doi.org/10.1016/j.earscirev.2017.06.004.
• H Svensen, S Planke, A Malthe-Sørenssen, B Jamtveit, R Myklebust, T Rasmussen-Eidem, SS Rey. Release of methane from a volcanic basin as a mechanism for initial Eocene global warming. Nature 429 (2004) 542–545.
• NB The new work on carbon emissions from LIPs is currently under peer review; please contact SMJ for advance copy.